Adjustable constant voltage space discharge tube



A ril 29, 1941. P. SPENCER 2,239,745

ADJUSTABLE CONSTANT VOLTAGE SPACE DISCHARGE TUBE Filed June 22, 193a 4 I I J v I I I 3 I I I I} 2 I I I I I .II I I I 6 I I I l/NsrAa/uz 2745/1 /ZEO 50mm: a 4 Harm/7' 0F 0.8. v 17.4. VDLTAGE & j W

Patented Apr. 29, 1941 ADJUSTABLE CONSTANT VOLTAGE SPACE DISCHARGE TUBE Percy L. Spencer, West Newton, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass, a corporation of Delaware Application June 22, 1938, Serial No. 215,147

9 Claims.

This invention relates to an electrical space drop remains constant with changes in current flowing through said tube. Such tubes have been used to maintain the voltage across a circuit at a predetermined constant value with changes in the voltage of the source feeding said circuit. However, heretofore the voltage drop across said tubes has been determined by the condition and configuration of the electrodes, the gas filling, and the general geometry of the tube. It has often been diflicult to reproduce a particular voltage drop in a series of tubes, and also the exact voltages secured in each case have been limited by the foregoing factors. In view of this situation, it is desirable to make a constant voltage tube in which the voltage drop may be adjusted at will to any predetermined value.

My invention contemplates the production of such a tube. One of the objects of my invention is to devise such a tube in which the voltage drop may be adjusted to a predetermined value at any time.

The foregoing and other objects of my invention will be best understood from the following description of an exemplification thereof, reference being had to the accompanying drawing wherein the figure shows a tube embodying my invention with certain parts theerof in crosssection together with a diagrammatic showing of a circuit in which the tube may be utilized.

The tube represented in the drawing comprises a hermetically-sealed envelope I having a reentrant stem 2 at the upper end of which is a press 3. The press 3 supports a cathode 4 and an anode 5. The tube is filled with an inert gas,

such as helium, argon or neon, at a pressure of the order of several millimeters. The cathode 4 consists of the relatively extended metal member preferably in cylindrical form. This metal member may be made of nickel, iron, or some other suitable metal. The surface of the cathode in some instances is left bare and in other instances in which lower voltage drop is desired may be coated with electron-emitting materials. In the particular form which I have illustrated, the cathode 4 is adapted to run-below the temperature at which electrons are emitted thermioni cally in any appreciable amount. Under these conditions the cathode operates as a glow discharge cathode in which the electrons are liberated therefrom primarily by ionic bombardment. The voltage drop at the cathode remains constant for all values of discharge current within the range of the normal glow discharge.

In previous devices of this kind the voltage drop through the tube has been dependent upon the nature of'the cathode, its surface, and the gas pressure. I have found, however, that the anode voltage drop and thus the voltage drop through the tube may be controlled by varying the conditions adjacent the surface of the anode. For this purpose I have constructed my anode 5 inthe form of a wire shown bent into a loop through which an electrical current may be passed. The flow of current through the wire 5 creates a magnetic field surrounding said wire. Therefore, as an electron liberated from the cathode 4 approaches the anode 5, it must cut through the lines of force of this magnetic field, and therefore is deflected by said field. The magnetic field adjacent the anode may be made very intense, and under these conditions a considerable opposition to the flow of the electrons to the anode is created. This opposition manifests itself in anincreased Voltage drop which, however, remains constant throughout said predetermined range of current variation flowing through the tube, provided the magnetic field around the anode is kept at a substantially constant value. The magnetic field around the anode can be made very intense without the necessity for passing large amounts of current through said anode by making the anode of a fine wire. For example, the wire may have a diameter of the order of .001 inch. The smaller the-diameter of said wire, the more intense will be the magnetic field immediately adjacent the surface of said wire with the predetermined amount of current flowing therethrough. Of course the magnitude of this magnetic field can likewise be controlled by the amount of current which is passed through the wire constituting the anode.

It is desirable that all of the anode construction to which the discharge can flow shall have such a magnetic field around it to prevent part of said anode from having a lower voltage drop. For this reason it is desirable to make the entire anode exposed to the discharge of the fine Wire described above. In some constructions special shielding arrangements for shielding from the discharge those parts of the anode which do not have the necessary magnetic field around them may be used. The tube described above may be provided with the usual base 6 having a plurality of contact prongs 1, whereby external electrical connections may be made. to the electrode ele ments within the tube.

The tube which I have illustrated may be utilized in a. variety of circuits. One of these circuits is shown in the drawing. This circuit consists of a source 8 of direct current. This source is one which is subjected to variations in voltage which it is desired to stabilize. The negative terminal of said source 8 is connected through a resistance 9 to the contact prong 1 connected to the cathode 4. The two ends of the anode are connected to two of the contact prongs, one of which is connected by a conductor II to a lead H extending to the positive terminal of the source 3. When the source 8 is energized, a discharge current will fiow between the oathode 4 and the anode 5 with a predetermined voltage drop dependent upon the various factors mentioned above. If the Voltage of the source 8 tends to increase, the space current between the cathode 4 and anode 5 will increase which will produce a drop in voltage across the resistance 9 to compensate exactly for the increase in voltage of the source 8. The voltage between the cathode 4 and anode 5, however, will remain constant. A similar action occurs when the voltage of the source 8 tends to decrease. Under these conditions the current flow between the cathode 4 and the anode 5 decreases and maintains the voltage between said electrodes at a constant value. Therefore, a load device I2 which is connected between the conductor II and the conductor I3 extending to the cathode prong 1 will have impressed upon it a constant Voltage.

If, however, the voltage drop between the cathode 4 and anode 5 is not exactly the value which it is desired to impress across the load device [2, an adjustment of the voltage drop may be made.

This is accomplished byconnecting one end of the wire anode 5 through a conductor M, and an adjustable resistance i5 to one terminal of a source of current It. The other terminal of said source of current is connected by a conductor H to the conductor iii, and thus to the other end of said wire anode 5. When current is passed through the wire anode 5 and the magnetic field set up around said anode, the voltage drop through the tube will increase, due to the efiect of said magnetic field upon the electron fiow, as indicated above. If it is desired to increase this voltage drop, the resistance I5 is adjusted so as to increase the fiow of current through the anode, while if a lower voltage drop is desired, the resistance I5 is adjusted so as to decrease the current. I have found that when the voltage drop is adjusted to any predetermined value, in accordance with the foregoing arrangement, said voltage drop remains fixed at that value throughout the rated current variation flowing through the tube.

Of course it is to be understood that the principles of my invention, as contained in the foregoing description, can be applied to other tube constructions. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of this invention.

What is claimed is:

1. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission and having a substant1ally constant voltage drop for all values of discharge current within a predetermined range, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said fiow of electrons, and means for varying the anode voltage drop from the value of the anode drop in absence of said means.

2. An electrical discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission and having a substantially constant voltage drop for all values of discharge current within a predetermined range, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said flow of electrons, and means for creating a predetermined magnetic field immediately adjacent the surface of said anode with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field.

3. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission and having a substantially constant voltage drop for all values of discharge current within a predetermined range, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said flow of electrons, said anode comprising an elongated electrical conductor, and means for passing a current through said conductor for creating a predetermined magnetic field immediately adjacent the surface of said anode with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field.

4. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission, an anode receiving a fiow of electrons from said cathode, said gas being at a pressure at which substantial ionization occurs between said cathode and anode upon the occurrence of said fiow of electrons, said anode comprising an elongated electrical conductor, and means for passing a current through said conductor for creating a predetermined magnetic field immediately adjacent the surface of said anode with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field.

5. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission and having a substantially constant voltage drop for all values of discharge current within a predetermined range, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said flow of electrons, said anode comprising an elongatedelectrical conductor, means for passing a current through said conductor for creating a predetermined magnetic field immediately adjacent the surface of said anode with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field, and means for varying the current through said anode conductor.

6. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission and having a substantially constant voltage drop for all values of discharge current within a predetermined range, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the oc-' currence of said flow of electrons, said anode comprising an elongated wire conductor, said wire having a diameter of the order of .001 inch, means for passing a current through said conductor for creating a predetermined magnetic field immediately adjacent the surface of said anode with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field.

7. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said flow of electrons, and means for varying the anode voltage drop from the value of the anode voltage drop in absence of said means.

8. An electrical space discharge device comprising an envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said flow of electrons, and means for creating a predetermined magnetic field immediately adjacent the surface of said anode with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field.

9. An electrical space discharge device comprising an. envelope containing an ionizable gas filling, a cathode operating throughout substantially its entire normal operation with a glow discharge below temperature of substantial thermionic emission, an anode receiving a flow of electrons from said cathode during operation, said gas being at a pressure at which substantial ionization occurs upon the occurrence of said flow of electrons, said anode comprising an elongated electrical conductor, and means for passing a current through said conductor for creating a predetermined magnetic field immediately adjacent the surface of said anode, with the lines of force thereof intercepting the discharge path between said cathode and anode for making the anode voltage drop greater than the anode voltage drop in absence of said magnetic field.

PERCY L. SPENCER. 

